Patent Document 1 discloses a pseudo base station apparatus which tests the operation of mobile communication terminals (for example, mobile phones) using W-CDMA, CDMA2000 (including CDMA2000 1X and CDMA2000EV-DO which are hereinafter generically referred to as “C2K”), and GSM, which are communication systems according to the related art. Next, the C2K system will be described as an example of the communication system according to the related art.
In recent years, an LTE (Long Term Evolution) system has been developed as a next-generation communication system for further improving the data transmission speed of the C2K system, which is a communication system according to the related art.
The LTE system uses OFDMA (Orthogonal Frequency Division Multiple Access) for downlink and SC-FDMA (Single Carrier Frequency Division Multiple Access) for uplink and requires the following communication speed: a downlink peak data rate of 100 Mbps or more and an uplink peak data rate of 50 Mbps or more (in a frequency bandwidth of 20 MHz). Many C2K communication service providers are expected to use the LTE system in the future.
However, there are maintenance problems of communication facilities or technical problems (in practice, the LTE system having a packet switching network is suitable for data communication and the existing C2K system having a circuit switching network is suitable for phone calls or SMS). Therefore, a method is considered which uses both the LTE and C2K systems at present, gradually expands the communication area of the LTE system, and finally changes the communication service to the LTE service while ending the C2K service.
There are mobile phones which do not perform LTE communication and C2K communication at the same time. When such a mobile phone is used, location registrations are needed to be done to both the nearest LTE base station and C2K base station. This method which registers the location to both the base stations using different communication systems to perform a smooth handover has been defined as a communication standard.
That is, the LTE base station can store base station information for the C2K base station and broadcast a mobile phone of its own base station information and the base station information about the C2K base station as broadcast information. In addition, the LTE base station can notify the location registration information of the mobile phone which communicates with the LTE base station to the C2K base station through a wired network. Therefore, the mobile phone can perform a location registration process, which should be originally performed with the C2K base station, with the LTE base station. Therefore, only a call connection process may be performed between the C2K base station and the mobile phone.
As such, for the period in which both the LTE and C2K services are available, CS Fallback (CSFB) is used which is one method in which, when the packet switching network wants to perform circuit switching communication, such as voice communication, it hands over the service area to a mobile communication system having a circuit switching network such that line exchange communication is performed. In this way, it is possible to appropriately perform a handover between the LTE base station and the C2K base station and perform communication with the base station corresponding to the service.
Patent Document 2 discloses a device which tests the handover operation of a mobile communication terminal between the base stations using different communication systems.